Location-based services (LBS) are a class of value-added services providing location-based navigation and inquiry services for users over a mobile communication network by using wireless location technologies in cooperation with a Geographic Information System (GIS), which represent a combination of the spatial information technology and the wireless communication technology. In recent years, progress in the radio technology and the wireless local area (WLAN) technology and increase of location service demands promote the development of the location technology. Demands on the LBS are ever increasing. The location technology is extremely important, especially in emergencies. Therefore, LBS-based wireless location applications see a broad and promising market.
Currently, LBS include three location methods: Global Positioning System (GPS) location, wireless network location, and hybrid location. The hybrid location is a combination of the GPS location and the wireless network location, and is the most commonly used location method. This is because if only the GPS receiver is used for location, a location failure might happen due to difficulty of receiving GPS signals from a satellite among blocks in downtown areas or within buildings. In the field of mobile communication, the following traditional location methods are available:
Cell of Origin (COO) is a location technology which determines the location of a user by collecting the identifier of a cell which the mobile station belongs to. This technology is simple but achieves poor accuracy, failing to satisfy requirements of majority of users.
Enhanced Observed Time Difference (E-OTD) is implemented by deploying reference points. The system distributes reference points among a plurality of stations deployed in a large area, as location measurement units covering the wireless network. Each reference point has an accurate clock source. When an E-OTD-enabled mobile phone and the location measurement units receive signals from at least three base stations, the time difference from each of the base stations to the mobile phone and the location measurement units can be calculated. Based on the calculated time differences, the location of the mobile phone is estimated. This solution is, however, complicated.
Assisted GPS (A-GPS) is a system where a plurality of GPS receivers are deployed at locations at which signals are successfully received from a satellite. In the A-GPS, the received assisted GPS signals are sent to a mobile phone over a communication network; and a mobile phone equipped with a GPS calculation chip calculates the location of the mobile phone according to the GPS location data transmitted over the communication network, with location accuracy of within 10 meters. However, this solution, compared with the E-TOD technology, has higher requirements on both the network and the mobile phone.
In addition, the Angle of Arrival (AOA) location technology and the Time of Arrival (TOA) location technology are available. The AOA location technology is to determine the location of a mobile station according to angles of arrival of signal from a mobile station to two base stations. The TOA location technology is to determine the location of a mobile station by measuring the time from being sent from the mobile station to arrival at a message measurement unit.
The prior art further provides a location method for use in a mobile communication system, where a mobile terminal is located by matching a group of actual signal parameter information acquired during location, and a base station identifier corresponding to each actual signal parameter information, with a statistical value for each group of signal parameters measured in advance in different sub-areas and a base station identifier corresponding to each actual signal parameter information. This improves location speed and accuracy. However, a mobile base station achieves a poor signal coverage, location accuracy according to the location method in the prior art still needs to be improved. In addition, if a large number of mobile terminals communicate with the base station for location, communication resources will be occupied.